/*
 * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "lzfP.h"

#if AVOID_ERRNO
# define SET_ERRNO(n)
#else

# include <errno.h>

# define SET_ERRNO(n) errno = (n)
#endif

#if USE_REP_MOVSB /* small win on amd, big loss on intel */
#if (__i386 || __amd64) && __GNUC__ >= 3
# define lzf_movsb(dst, src, len)                \
   asm ("rep movsb"                              \
        : "=D" (dst), "=S" (src), "=c" (len)     \
        :  "0" (dst),  "1" (src),  "2" (len));
#endif
#endif

#if defined(__GNUC__) && __GNUC__ >= 5
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
#endif

unsigned int
lzf_decompress(const void *const in_data, unsigned int in_len,
               void *out_data, unsigned int out_len) {
    u8 const *ip = (const u8 *) in_data;
    u8 *op = (u8 *) out_data;
    u8 const *const in_end = ip + in_len;
    u8 *const out_end = op + out_len;

    do {
        unsigned int ctrl = *ip++;

        if (ctrl < (1 << 5)) /* literal run */
        {
            ctrl++;

            if (op + ctrl > out_end) {
                SET_ERRNO (E2BIG);
                return 0;
            }

#if CHECK_INPUT
            if (ip + ctrl > in_end) {
                SET_ERRNO (EINVAL);
                return 0;
            }
#endif

#ifdef lzf_movsb
            lzf_movsb (op, ip, ctrl);
#else
            switch (ctrl) {
                case 32:
                    *op++ = *ip++;
                case 31:
                    *op++ = *ip++;
                case 30:
                    *op++ = *ip++;
                case 29:
                    *op++ = *ip++;
                case 28:
                    *op++ = *ip++;
                case 27:
                    *op++ = *ip++;
                case 26:
                    *op++ = *ip++;
                case 25:
                    *op++ = *ip++;
                case 24:
                    *op++ = *ip++;
                case 23:
                    *op++ = *ip++;
                case 22:
                    *op++ = *ip++;
                case 21:
                    *op++ = *ip++;
                case 20:
                    *op++ = *ip++;
                case 19:
                    *op++ = *ip++;
                case 18:
                    *op++ = *ip++;
                case 17:
                    *op++ = *ip++;
                case 16:
                    *op++ = *ip++;
                case 15:
                    *op++ = *ip++;
                case 14:
                    *op++ = *ip++;
                case 13:
                    *op++ = *ip++;
                case 12:
                    *op++ = *ip++;
                case 11:
                    *op++ = *ip++;
                case 10:
                    *op++ = *ip++;
                case 9:
                    *op++ = *ip++;
                case 8:
                    *op++ = *ip++;
                case 7:
                    *op++ = *ip++;
                case 6:
                    *op++ = *ip++;
                case 5:
                    *op++ = *ip++;
                case 4:
                    *op++ = *ip++;
                case 3:
                    *op++ = *ip++;
                case 2:
                    *op++ = *ip++;
                case 1:
                    *op++ = *ip++;
            }
#endif
        } else /* back reference */
        {
            unsigned int len = ctrl >> 5;

            u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;

#if CHECK_INPUT
            if (ip >= in_end) {
                SET_ERRNO (EINVAL);
                return 0;
            }
#endif
            if (len == 7) {
                len += *ip++;
#if CHECK_INPUT
                if (ip >= in_end) {
                    SET_ERRNO (EINVAL);
                    return 0;
                }
#endif
            }

            ref -= *ip++;

            if (op + len + 2 > out_end) {
                SET_ERRNO (E2BIG);
                return 0;
            }

            if (ref < (u8 *) out_data) {
                SET_ERRNO (EINVAL);
                return 0;
            }

#ifdef lzf_movsb
            len += 2;
            lzf_movsb (op, ref, len);
#else
            switch (len) {
                default:
                    len += 2;

                    if (op >= ref + len) {
                        /* disjunct areas */
                        memcpy (op, ref, len);
                        op += len;
                    } else {
                        /* overlapping, use octte by octte copying */
                        do
                            *op++ = *ref++;
                        while (--len);
                    }

                    break;

                case 9:
                    *op++ = *ref++; /* fall-thru */
                case 8:
                    *op++ = *ref++; /* fall-thru */
                case 7:
                    *op++ = *ref++; /* fall-thru */
                case 6:
                    *op++ = *ref++; /* fall-thru */
                case 5:
                    *op++ = *ref++; /* fall-thru */
                case 4:
                    *op++ = *ref++; /* fall-thru */
                case 3:
                    *op++ = *ref++; /* fall-thru */
                case 2:
                    *op++ = *ref++; /* fall-thru */
                case 1:
                    *op++ = *ref++; /* fall-thru */
                case 0:
                    *op++ = *ref++; /* two octets more */
                    *op++ = *ref++; /* fall-thru */
            }
#endif
        }
    } while (ip < in_end);

    return op - (u8 *) out_data;
}

#if defined(__GNUC__) && __GNUC__ >= 5
#pragma GCC diagnostic pop
#endif
